Ofnuts information is all you need to know but sometimes not so easy for a beginner to understand.
During covid lockdown I was making bespoke birthday cards, great fun, but my stock of nice old A4 satin paper is running low.
The main thing is to start off with a a suitable resolution before you even create a design.
For 5 inches x 5 inches use 300 ppi That equals an image size of (5 x 300) 1500 x 1500 pixels.
( but you might need to take any printer imposed margins into account )
Smaller than that and quality will suffer. Bigger you will be ok All will print the same size.
During covid lockdown I was making bespoke birthday cards, great fun, but my stock of nice old A4 satin paper is running low.
The main thing is to start off with a a suitable resolution before you even create a design.
For 5 inches x 5 inches use 300 ppi That equals an image size of (5 x 300) 1500 x 1500 pixels.
( but you might need to take any printer imposed margins into account )
Smaller than that and quality will suffer. Bigger you will be ok All will print the same size.